MARTINSRIED, GermanyGPC Biotech AG and Pharmion Corporation have announced positive results for the companies' oral platinum agent satraplatin in an interim analysis of the double-blind, randomized phase III registration trial. The study, known as SPARC (Satraplatin and Prednisone Against Refractory Cancer), evaluated satraplatin plus prednisone vs placebo plus prednisone as second-line treatment in 950 patients with hormone-refractory prostate cancer. The study data show that improvements in progression-free survival (PFS) with satraplatin are highly significant (P < .00001). Patients who received satraplatin/prednisone had a 40% reduction in risk of disease progression (HR 0.6, 95% CI 0.5-0.7), compared with the prednisone/placebo patients.
The improvement seen in PFS in the satraplatin patients increased over time. Progression-free survival at the median (50th percentile) showed a 13% improvement (11 weeks vs 9.7 weeks for the controls). At the 75th percentile, the improvement was 89% (36 weeks vs 19 weeks). At 6 months, 30% of patients in the satraplatin arm had not progressed, compared with 17% in the control arm. At 12 months, 16% of patients on satraplatin had not progressed vs 7% of controls. All of these analyses were conducted on an intent-to-treat basis.
The improvement in progression-free survival in the satraplatin arm was not affected by the type of prior chemotherapy. In particular, the companies said, the improvement was seen equally for patients who had received prior docetaxel (Taxotere), as well as those who received other types of chemotherapy.
In accordance with the recommendation of the independent Data Monitoring Board for the SPARC trial, patients who have not progressed will continue to be treated, and all patients will be followed for overall survival. With approximately half of the patients from the trial still alive, the companies currently expect to have final overall survival results in the fall of 2007.